Not an iPhone question, but maybe you can still help ...

So I have a USB plug in my car so I've been loading my iTunes music on a jump drive and playing it through my stereo that way .. The thing is, my car will only read mp3 and a lot of my music on my iTunes is m4a or some random file name .. How do I convert my music to mp3? And is there a way to just be like, "Convert everything that's not an mp3 to mp3 at one time" or do I have to go file by file? Thanks

Look for your import preferences in iTunes and make sure they're set to import using mp3. Then highlight your non-mp3 songs (easy to do if you sort by file type first, then select all non-mp3 tunes), then right click and choose "create mp3 version."

Just started the process, I had 424 songs that weren't mp3's! geez haha .. And I answered my question there cuz I see I will have to delete the old files after they convert, but at least I have em all in a row now that I sorted by file type. Thanks again!